Astronomy & space · University
Exoplanet transits and radial velocities · revision notes
A planet crossing a star's visible disk can cause a periodic brightness dip. For an idealized small dark planet and uniform stellar disk, depth≈(Rp/Rstar)².
Key ideas and conditions
Transit method
A planet crossing a star's visible disk can cause a periodic brightness dip. For an idealized small dark planet and uniform stellar disk, depth≈(Rp/Rstar)².
Radial velocity
A star and planet orbit their common centre of mass. Periodic line-of-sight stellar velocity changes can be inferred from spectral shifts.
Selection
Neither method detects every planet equally well. Orbital orientation, noise, stellar activity and observational duration affect sensitivity.
Confirmation
A candidate signal needs checks against false positives. A transit alone is not proof of life or a complete atmospheric measurement.
Explain without looking
- Why does the uniform-disk transit-depth formula not describe every detailed transit light curve?
- Does detecting a planet by transit establish that it supports life?
Further reading and review references
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